Method of making a thin film magnetic head including protected via connections through an electrically insulative substrate

ABSTRACT

A method is provided for fabricating a thin film magnetic head including a plurality of layered components. One or more vias are formed through an electrically insulative substrate which includes first and second opposed major surfaces. The via includes an interior side surface. The via is filled with electrically conductive material which is situated in contact with the interior side surface of the via. A via connective member is thus formed which extends between the first and second surfaces of the substrate. A protective via cap is formed atop the via connective member to protect the via connective member from subsequent etching operations. A thin film head is formed atop the first surface of the substrate by building up components of the head layer by layer. This forming a thin film head step includes the step of forming a coil for exciting the head by etching, with an etchant, portions of a layer of electrically conductive material within the head. The via protective cap is fabricated from a material which is substantially resistant to etching by the etchant. In this manner the via conductive member is shielded from the potentially deleterious effects of etching. The via connective member typically couples the coil to circuitry external to the thin film head.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This application is a division of application Ser. No. 08/296,839, filedAug. 26, 1994 now abandoned.

This patent application is related to the patent application entitled"METHOD OF FABRICATING A THIN FILM MAGNETIC HEAD INCLUDING LAYEREDMAGNETIC SIDE POLES", patent application Ser. No. 08/297,186 by Malhotraet-al., filed concurrently herewith and assigned to the same assignee,abandoned in favor of Ser. No.: 08/641,345 now issued as U.S. Pat. No.5,748,417 issued on May 5, 1998, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to magnetic recording/playback headsand, more particularly, to connective structures and techniques for thinfilm magnetic recording/playback heads.

2. Description of Related Art

In the continuing drive for increased storage density in magnetic mediastorage devices, thin film magnetic heads have been developed. Asopposed to earlier types of magnetic heads, the fabrication of whichinvolves significant piecework and manual handling of individual parts,thin film magnetic heads take advantage of semiconductor fabricationprocesses to form a large number of heads simultaneously on a commonsubstrate or wafer.

One such head which is formed by a semiconductor thin film process isdisclosed in the article, "A New Thin Film Head Generation IC Head" byJ.P. Lazzari et al., IEEE Transactions on Magnetics,, Vol. 25, No. 5,September 1989. A cross-sectional view of the Lazzari head isillustrated in FIG. 1 as head 10. Head 10 is fabricated within a recess15 in a silicon substrate 20. A gap 25 is shown in the uppermost portionof a magnetic layer or yoke 30 situated within recess 15. Head 10 isshown positioned adjacent magnetic recording media 35. A magnetic coil40 is wound around magnetic yoke 30. A plurality of sliders withrespective heads 10 thereon are fabricated from a common silicon waferor substrate using semiconductor thin film processes. The sliders arethen diced up into individual slider assemblies.

To achieve electrical connection to the coils of the head, a throughhole connection 45 is made in the silicon substrate. The walls of thehole are coated with an insulator layer 50 and the center of the hole isfilled with a conductive layer 55 as shown in FIG. 1.

Efficient connection to the ends of the coil structure of a thin filmhead is one problem which the thin film head designer faces. Suchconnections need to be achieved in a manner which is compatible with thefabrication of the remaining structures of the thin film head.

SUMMARY OF THE INVENTION

One advantage of the thin film head of the present invention is theestablishment of electrical connections to the coil structure of a thinfilm head using a minimum number of connective structures.

Another advantage of the thin film head of the present invention is thatthe disclosed thin film head can be fabricated without excavating arecess within the substrate to contain the head.

Still another advantage of the thin film head of the present inventionis that the disclosed head can be fabricated in large quantities usingthin film semiconductor fabrication equipment.

In accordance with one embodiment of the present invention, a thin filmmagnetic head is provided which includes an electrically insulativesubstrate having first and second opposed major surfaces, the substrateincluding a via between the first and second surfaces, the via includingan interior side surface. The head also includes a via connective memberof electrically conductive material situated within the via in contactwith the interior side surface of the via and extending between thefirst and second surfaces of the substrate. The head further includes aprotective via cap situated atop the via connective member at the firstsurface of the substrate. The head still further includes a lower polemember of magnetic material situated on the first surface of thesubstrate and having first and second ends. The head also includes firstand second side pole members of magnetic material situated at the firstand second ends, respectively, of the lower pole member, the first andsecond side pole members being built up from a plurality of layers ofmagnetic material deposited layer upon layer, the first and second sidepole members including tops and bottoms. The head further includes aninsulative body situated about the first and second side poles and builtup from a plurality of layers of electrically insulative material. Thehead also includes a conductor coil layer of electrically conductivematerial situated within the insulative body and around one of the firstand second side pole members, the coil being formed by etching portionsof the coil layer with an etchant.

The head further includes an insulative pedestal situated at the tops ofthe first and second side pole members, the insulative pedestalextending above the plane of the insulative body below and surroundingthe tops of the first and second side pole members. The head stillfurther includes first and second magnetic poles coupled to the tops ofthe first and second side pole members respectively to form a gap regiontherebetween. In the disclosed head, the via protective cap isfabricated from a material which is substantially resistant to etchingby the etchant. In this manner, the integrity of the via connectivemember is not degraded by etchants which are used in the fabrication ofthe head. While one via connective member is mentioned above, it shouldbe understood that multiple via connective members fabricated asdescribed may actually be employed in a particular thin film magnetichead. These via connective members are generally used to establishelectrical connection between the coil structure within the head andexternal electrical circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel are specifically setforth in the appended claims. However, the invention itself, both as toits structure and method of operation, may best be understood byreferring to the following description and accompanying drawings.

FIG. 1 is a cross section of a conventional thin film magnetic head.

FIG. 2A is a plan view of a substrate with via holes employed by oneembodiment of the magnetic head of the invention.

FIG. 2B is a cross section of the magnetic head of FIG. 2A taken alongsection line 2B--2B.

FIG. 3 is a plan view of the magnetic head of FIG. 2A with a seed layeradded.

FIG. 4A is a plan view of the magnetic head of FIG. 3 with an insulativelayer and, open region formed therein.

FIG. 4B is a cross sectional view of the magnetic head of FIG. 4A takenalong section line 4B--4B.

FIG. 5 illustrates a plurality of magnetic heads being fabricated on acommon substrate.

FIG. 6A is a plan view of the magnetic head of FIG. 4A showing an earlystage of side pole build-up

FIG. 6B is a cross sectional view of the magnetic head of FIG. 6A takenalong section line 6B--6B.

FIG. 7A is a plan view of the magnetic head of FIG. 6A showing theplacement of a lower coil structure.

FIG. 7B is a cross sectional view of the magnetic head of FIG. 7A takenalong section line 7B--7B.

FIG. 8A is a plan view of the magnetic head of FIG. 7A showing aninsulative layer on the lower coil structure.

FIG. 8B is a cross sectional view of the magnetic head of FIG. 8A takenalong section line 8B--8B.

FIG. 9A is a plan view of the magnetic head of FIG. 8A showing placementof an upper coil structure.

FIG. 9B is a cross sectional view of the magnetic head of FIG. 8A takenalong section line 9B--9B.

FIG. 10A is a plan view of the magnetic head of FIG. 9A showing aninsulative layer on the upper coil structure.

FIG. 10B is a cross sectional view of the magnetic head of FIG. 10Ataken along section line 10B--10B.

FIG. 11A is a plan view of the magnetic head of FIG. 10A showingplacement of a seed layer and a connective grounding strip.

FIG. 11B is a cross sectional view of the magnetic head of FIG. 11Ataken along section line 11B--11B.

FIG. 12 is a cross sectional view of the magnetic head of FIG. 11Bshowing placement of an insulative pedestal thereon.

FIG. 13A is a cross sectional view of the magnetic head of FIG. 13Bshowing the further build-up of the magnetic side poles.

FIG. 13B is a close-up plan view of a portion of the head of FIG. 13Ashowing the side pole and insulative pedestal area.

FIG. 14A is a cross sectional view of the magnetic head of FIG. 14Bshowing the addition of a first magnetic pole at the top of the magneticyoke structure of the head.

FIG. 14B is a close-up plan view of a portion of the head of FIG. 14Ashowing the first magnetic pole.

FIG. 15A is a close-up plan view of a portion of the head of FIG. 14Ashowing the gap region of the head.

FIG. 15B is a cross sectional view of the magnetic head of FIG. 15Ashowing the addition of a gap region.

FIG. 16A is a close-up plan view of the side pole and gap region of themagnetic head of FIG. 15A showing the addition of a second magnetic poleat the top of the magnetic yoke structure of the head.

FIG. 16B is a cross sectional view of the magnetic head of FIG. 16Ataken along section line 16B--16B and showing the addition of a secondmagnetic pole.

FIG. 17A is a close-up plan view of the side pole and gap region of themagnetic head of FIG. 16A after addition of an adhesion layer and adiamond-like carbon wear layer to the top of the head.

FIG. 17B is a cross sectional view of the magnetic head of FIG. 17Ataken along section line 17B--17B.

FIG. 18 is a cross sectional view of the magnetic head of FIG. 17Bshowing the magnetic head after a diamond-like carbon wear layer andadhesion layer are patterned and etched in regions other than theinsulative pedestal.

FIG. 19A is a close-up view of, the side pole and gap region of themagnetic head when fabrication is complete.

FIG. 19B is a cross section view of the magnetic head of FIG. 19A takenalong section line 19B--19B.

FIG. 20 is a plan view of the bottom side of the thin film head of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

I. VIA CONNECTION FABRICATION--GENERAL DESCRIPTION

FIG. 2A shows a portion of a thin film head 100 which is situated on aninsulative substrate 105 such as a ceramic, alumina or othernonconductive substrate. Substrate 105 includes opposed surfaces 105Aand 105B. Via holes 110 are formed in substrate 105 and are filled withan electrically conductive material to create conductive paths throughsubstrate 105 at the locations shown. Laser drilling or other highprecision via formation technique may be employed to form via holes 110.Via holes 110 are filled with electrically conductive material such asplated copper, thick film processed gold, or sintered tungsten andcopper, for example, to form via connective members 112A, 112B and 112C.Connective members 112A and 112C will subsequently be coupled to theends of a coil structure and connective member 112B will be coupled toground. In one embodiment of the invention wherein the magnetic head isungrounded, via hole 112B is omitted. In actual practice, substrate 105is a wafer on which the FIG. 2A pattern is replicated thousands oftimes.

A seed layer 115 of an electrically conductive material suitable forplating is sputtered on substrate surface 105A. For example, seed layer115 may be fabricated from Cr--NiV, namely, a chrome or otheradhesion-promoting layer followed by a non-magnetic nickel-vanadium 7%film. Via caps 120 are patterned using photolithographic techniques andplated on seed layer 115 at the tops of vias 110 as shown in FIGS. 2Aand 2B. More specifically, to pattern via caps 120, a photoresist layer(not shown) is deposited on seed layer 115 and patterned to includeopenings above connective members 112A, 112B and 112C at which theformation of respective via caps 120 is desired. Plating is thenconducted in these openings using seed layer 115 as the seed. Thephotoresist is then removed, thus leaving patterned via caps 120. Asused in this document, the term "patterning" will mean the formation ofa particular layer such that the layer exhibits a specified pattern,such as described with respect to the formation of via caps 120 above,for example.

Via caps 120 are fabricated from NiFe by any suitable deposition orplating process. It is noted that later in the process described herein,portions of seed layer 115 will be removed by sputter etching. While inthe particular example described, via caps 120 are fabricated from NiFe,in actual practice via caps 120 can be fabricated from other conductivematerials which would not be attacked by the particular etchant used tolater remove Cr--Cu seed layers 185, 230 and 275. Via caps 120 areregarded as being a part of via connective members 112A, 112B and 112C.

Seed layer 115 is also used to pattern and NiFe plate photolithographicalignment targets (not shown) for registration of subsequent layers. Theexposed portions of seed layer 115 are then sputter etched away leavingvia caps 120 and the alignment targets intact. It should be appreciatedthat seed layer 115 served as a sacrificial layer for the purpose ofenabling plating of via caps 120.

II. THIN FILM HEAD BUILD-UP PROCESS

In the next step of the process, a Cr--NiV seed layer 130 is formed onthe structure of FIG. 2B after seed layer 115 is etched away. Seed layer130 is formed in the shape of a ground structure 125 which extendsaround the periphery of head 100 on substrate 105 and laterally acrossthe middle of head 100 as shown in FIG. 3. Open regions 117A and 117Bare thus formed in seed layer 130 which respectively isolate viaconnective members 112A and 112C from ground structure 125 and viaconnective member 112B. In the embodiment depicted in FIG. 3, viaconnective member 112B is coupled to ground structure 125. To actuallyform seed layer 130, a "lift-off" process is used. In this "lift-off"process, photoresist (not shown) is patterned covering open regions 117Aand 117B (see FIG. 3). Seed layer 130 is then sputtered on the entireupper surface of the partially completed head 100. The photo-resistwhich covers open regions 117A and 117B is now "lifted-off" head 100. Toaccomplish this lift-off, the partially complete head 100 is placed inan ultrasonic bath including a photoresist solvent such as acetone, forexample. The seed layer 130 is sufficiently thin such that it does notcover photoresist layer at open regions 117A and 117B very well. In thismanner, there are sufficient avenues of attack by which the solvent canget through seed layer 130 at the edges of open regions 117A and 117B todissolve the photoresist layer at open regions 117A and 117B. When thephotoresist layer at open regions 117A and 117B is thus dissolved, theportions of seed layer 130 immediately above open regions 117A and 117Bliftoff and float away. The region of head 100 at open regions 117A and117B is thus void of seed layer 130 as shown in FIG. 33.

An insulative layer 135 of photoresist is patterned on head 100 as shownin FIG. 4A and FIG. 4B. Insulative layer 135 is cured with an electronbeam. Exposing the photoresist to an E-beam for a time within the rangeof approximately 20 minutes to approximately 40 minutes is found toproduce acceptable curing results. Insulative layer 135 includes an openregion 140 for receiving the lowermost portion of a magnetic yoke 145therein. More particularly, a layer 150 of magnetic material such asNiFe is patterned and plated on seed layer 130 within open region 140 toform the lowermost portion of magnetic yoke 145. Magnetic layer 150exhibits a thickness of approximately 5 microns to approximately 6microns in this particular embodiment. When reference is made to"magnetic layers" or other magnetic structures in this document, itshould be understood that layers of magnetically permeable material arebeing referenced. Magnetic layer 150 forms the bottom pole of magneticyoke 145. Seed layer 130, or more specifically the middle section of theground structure 125 thereof, acts as a base upon which magnetic yoke145 is built up layer by layer. Magnetic layer 150 is plated up to alevel such that it is level with insulative layer 135. For convenience,one half of head 100 is depicted in FIG. 4A and subsequent figures. Itshould be understood that substantially the same structure as shown inFIG. 4A and the subsequent figures is repeated to form the actual head.More particularly, in the particular embodiment shown, head 100 issymmetric about major axis 155 such that head 100 actually includes tworecording or playback portions. In actual practice, a plurality of heads100 are fabricated simultaneously on a common semiconductor substrate105 as shown in FIG. 5. For example, 5000 or more heads may befabricated at the same time on the same substrate. FIG. 5 shows anotherembodiment of head 100, namely an ungrounded version in which viaconnective member 112B is omitted.

An insulative layer 160 of photoresist is patterned on head 100 as shownin FIG. 6A and 6B. Insulative layer 160 is electron beam cured toprovide a planar surface as illustrated. The thickness of insulativelayer 160 in this particular embodiment is approximately 2 microns.Insulative layer 160 includes open regions 165 and 170 in whichrespective magnetic side poles are built up. More specifically, amagnetic side pole portion 175 is plated in open region 165 up to aheight which is level with insulative layer 160, and a magnetic sidepole portion 180 is plated in open region 170 up to a height which islevel with insulative layer 160.

A seed layer 185 is sputtered on insulative layer 160 of the partiallyformed head 100 of FIG. 6A to form a plating base for a lower coil layer190 as shown in FIG. 7A. Seed layer 185 is drawn sufficiently thin suchthat it does not appear to have significant vertical dimension in FIG.7A. Seed layer 185 is fabricated from CrCu in one embodiment.

A lower coil layer 190 is formed on seed layer 185 as shown. One way toform lower coil member 190 is to deposit a layer of photoresist (notshown) on seed layer 185. This photoresist layer is then patterned usingconventional photolithographic techniques which includes photoresistapplication, masking, exposure, developing, and so forth. Morespecifically, the photoresist layer is patterned to cover the entiresurface of seed layer 185 except for openings at the locations where thecoil elements of lower coil layer 190 are to be formed. Head 100 is thensubjected to a plating bath of copper. Copper is thus plated in theopenings of the photoresist layer to form lower coil layer 190. Thethickness of coil layer 190 is within the range of approximately 3μ toapproximately 3.5μ at this stage.

Lower coil layer 190 includes a connective strip 195 made ofelectrically conductive material which couples an end 190A of coil layer190 to the via cap 120 of via connective member 112A. Copper plating maybe used to fabricate connective strip 195 as part of the above step offorming lower coil layer 190. The remaining end 190B of lower coil layer190 is located at the center of the lower coil. Head 100 is then etchedto remove seed layer 185 from those portions of head 100 not protectedby lower coil layer 190.

An insulative layer 200 of photoresist is patterned on head 100 abovelower coil layer 190 leaving an open region 205 for access to coil end190B as shown in FIGS. 8A and 8B. The thickness of insulative layer 200is within the range of approximately 5μ to approximately 6μ Insulativelayer 200 is also patterned to leave open regions 210 and 215 above sidepole portion 175 and side pole portion 180, respectively. Insulativelayer 200 is electron beam cured. Insulative layer 200 electricallyisolates lower coil layer 190 from structures subsequently placed abovelayer 190.

Magnetic side pole portions 220 and 225 are plated on side pole portions175 and 180, respectively, as shown in FIGS. 8A and 8B. Side poleportions 220 and 225 are plated with a magnetic material such as NiFe upto a level even with that of insulative layer 200.

A seed layer 230 is sputtered on insulative layer 200 of the partiallyformed head 100 of FIG. 8B to form a plating base for an upper coillayer 235. Seed layer 230 is drawn sufficiently thin such that it doesnot appear to have significant vertical dimension in FIG. 8B. Seed layer230 is fabricated from CrCu in one embodiment. Upper coil layer 235 ispatterned and copper plated on seed layer 230 as shown in FIG. 9A and9B. FIG. 9B is a simplified cross-section of head 100 at the describedstage of fabrication in which structures in back of upper coil layer 235are not shown in order to emphasize upper coil layer 235. In thisparticular embodiment, upper coil layer 235 is substantially similar ingeometry to lower coil layer 190 and is fabricated using substantiallythe same technique. However, other coil arrangements are possible ifdesired. Head 100 is then etched to remove seed layer 230 from thoseportions of head 100 not protected by upper coil layer 235.

Upper coil layer 235 includes a connective strip 237 made ofelectrically conductive material which couples an end 235A of upper coillayer 235 to the via cap 120 of via connective member 112C. Copper maybe used to fabricate connective strip 237. The remaining end 235B ofupper coil layer 235 is coupled to lower coil end 190B through openregion 205, shown later in FIG. 10B, by a plated connectiontherebetween.

An insulative layer 240 of photoresist material is deposited andpatterned on head 100 as shown in FIGS. 10A and 10B. Insulative layer240 electrically isolates upper coil layer 235 from the other structuresof head 100. Insulative layer 240 includes open regions 245 and 250 intowhich magnetic side pole portions 255 and 260 are respectively plated.More specifically, magnetic side pole portions 255 and 260 are plated upto a level even with insulative layer 240 as shown in FIG. 10B.

Magnetic side pole portions 175, 220 and 255 together form a first sidepole 265. Magnetic side pole portions 180, 225 and 260 together form asecond side pole 270. First side pole 265, second side pole 270 andbottom pole 150 together form a significant portion of magnetic yoke145.

A seed layer 275 fabricated of CrCu material is formed on the uppersurface of the head structure 100 as shown in FIG. 11B. Seed layer 275is sputtered, patterned and chemically etched on the upper surface ofhead 100 to include an open region 280 above the side pole structurealso as shown in FIG. 11B. Seed layer 275 is formed by an adhesion layerof chromium (Cr) on the upper surface of head 100 followed by a layer ofcopper (Cu). The chromium adhesion layer enhances the adherence of thecopper portion of seed layer 275 to upper surface of head 100.

The primary requirement in selection of the material for seed layer 275is that seed layer 275 be chemically etchable without damage to theexposed NiFe. Copper is an example of a material that meets thisrequirement and is also used for the coil seed layers. Chrome is used asthe adhesion layer for copper. It is noted that a titanium-tungsten seedlayer (Ti 10%; W 90%) which wet etches easily can also be used for seedlayer 275.

Protective caps 285 and 29.0 are patterned over connective strips 195and 237, respectively. Caps 285 and 290 are fabricated from NiFe byplating in one embodiment. A material such as nickel, nickel-phosphorus7-10%, or gold may be used to provide environmental protection for theunderlying plated copper connective strips.

In an embodiment of head 100 wherein head 100 is grounded, a groundingconnective strip 295 is also patterned and plated in the same processstep as protective caps 285 and 290. Grounding strip 295 connects groundvia connective member 112B and magnetic yoke 145 through seed layer 130.Grounding strip 295 is fabricated from the same material as protectivecaps 285 and 290 in this particular embodiment.

An electrically insulative layer of photoresist is patterned andelectron beam cured to form a protrusion or pedestal 300 on the upperportion of head 100 as shown in FIG. 12. Insulative pedestal 300exhibits a substantially rectangular geometry with rounded corners inthis particular embodiment, although other geometries may be used ifdesired. Insulative pedestal 300 includes open regions 305 and 310 forside poles 265 and 270 of the magnetic yoke. Open regions 305 and 310are filled with magnetic material by plating side poles 265 and 270 withNiFe up to the level of the top of insulative layer 300 as shown in FIG.13A. Magnetic side pole portions 315 and 320 are thus formed in openregions 305 and 310. Magnetic side pole portions 315 and 320 form theuppermost parts of first side pole 265 and second side pole 270,respectively.

A frame 325 of magnetic material, for example NiFe, is patterned aroundinsulative pedestal 300 at the same time that magnetic side poleportions 315 and 320 are plated. Plating or other suitable depositiontechnique is used to form frame 325. Frame 325 exhibits a thickness ofapproximately 5μ in this particular embodiment. Seed layer 275 acts asthe seed for the plating of frame 325. Frame 325 exhibits asubstantially rectangular shape in this particular embodiment andsurrounds insulative pedestal 300 which forms the inner boundary offrame 325 as seen in FIG. 13B. Shapes other than rectangular can be usedfor frame 235 as long as frame 325 substantially surrounds, and islocated immediately adjacent to, pedestal 300. Frame 325 serves tostiffen insulative pedestal 300 and may provide electrical shielding ofthe contained structures. FIG. 13B is a close-up view of the coil andside pole regions of head 100 at the present stage in the fabrication ofhead 100. Alternatively, side pole portions 315 and 320 are fabricatedas before, but frame 325 is subsequently patterned and plated withnon-magnetic NiP alloy up to a level even with the top of insulativepedestal 300. The innermost boundary of seed layer 275 which abuts itsopen region 280 is shown in dashed line in FIG. 13B. The exposed CrCuseed layer 275 is removed by wet chemical etching.

Referring now to FIGS. 3, 14A and 14B, a layer of photoresist ispatterned covering open regions 117A and 117B (see FIG.3) and furthercovering side poles 265 and 270 (see FIG.14A and 14B). A Cr--NiV seedlayer 330 is sputtered on the exposed upper surfaces of head 100. Thephoto-resist is stripped as in the earlier-described "lift-off" process,thus "lifting off" the sputtered Cr--NiV film from regions 117A and117B. During this photoresist stripping step, the photoresist above sidepoles 265 and 270 is removed to form open regions 335 and 340 as shownin FIG. 14A. Side poles 265 and 270 are thus exposed.

A first magnetic pole 345 is patterned at the top of magnetic yoke 145as shown in FIG. 14A and 14B. First magnetic pole 345 is fabricated byplating a magnetic material such as NiFe on side pole 265 and on aportion of seed layer 330 adjacent side pole 265. Magnetic controlregions 350 and 355, which are adjacent both sides of first magneticpole 345, may be patterned and plated at the same time as first pole345. Magnetic control regions 350 and 355 serve to better control localplating current density which influences NiFe composition and enhancesthe effect of the easy axis magnetic orienting field of betweenapproximately 1000 Gauss to approximately 10,000 Gauss, provided by anexternal magnet during the first magnetic pole plating step, to give adesired magnetic domain structure in the magnetic pole piece. Head 100is exposed to the same magnetic field throughout the duration ofbuilding up the various magnetic layers thereof.

A substantially rectangular gap region 360 of non-magnetic material isplated adjacent pole end 345A as shown in FIG. 15A and the head crosssection of FIG. 15B. One non-magnetic material which may be used tofabricate gap region 360 is NiP. Diamond-like carbon is another materialwhich may be chemically vapor deposited as gap region 360.

A second magnetic pole 365 is patterned and plated at side pole 270 atthe top of magnetic yoke 145 as shown in FIGS. 16A and 16B. Secondmagnetic pole 365 includes a pole end 365A which is situated adjacentpole end 345A and which is separated from pole end 345A by gap region360. It is noted that pole 345 becomes narrower from side pole 265 topole end 345A. Similarly, pole 365 becomes narrower from side pole 270to pole end 365A. This gives poles 345 and 365.a bow tie-like appearancein this particular embodiment. Other pole geometries may be used aswell. Pole ends 345A and 365A are alternatively referred to as gap ends.First magnetic pole 345 and second magnetic pole 365 exhibit a thicknessof approximately 5μ.

Magnetic control regions 370 and 375 are patterned and plated adjacentboth sides of second pole 365 to enhance magnetic control as shown inFIG. 16A. Control regions 350, 355, 370 and 375 are fabricated from amagnetic material such as the material used to fabricate second magneticpole 365. For optimal wear performance, the area of NiFe exposed to therecording media should be minimized. Thus, to avoid possible magneticeffects that may degrade recording performance, NiFe plated magneticcontrol regions 350, 355, 370 and 375 are patterned with photoresist andetched away leaving a pole geometry seen in FIG. 17A.

Magnetic side pole portions 175, 220, 255 and 315 together make up afirst side pole which is shown collectively as side pole 265 in FIG.16B. Magnetic side pole portions 180, 225, 260 and 320 together make upa second magnetic side pole which is shown collectively as side pole 270in FIG. 16B. Magnetic yoke 145 is collectively made up of bottommagnetic layer 150, side poles 265 and 270, and magnetic poles 345 and365.

The exposed seed layer 330 is removed by sputter etching. Alternatively,seed layer 330 is not etched, but is permitted to remain. A siliconadhesion layer 380 is sputtered on the exposed upper surface of head 100as shown in FIG. 17B. A diamond-like carbon (DLC) protective wear layer385 is then deposited on adhesion layer 380. Adhesion layer 380 enablesDLC layer 385 to stick to the upper surface of head 100. This siliconadhesion layer typically exhibits a thickness within the range ofapproximately 400A° to approximately 1000A°. This silicon adhesion layerexhibits a nominal thickness of approximately 600A° in a preferredembodiment.

DLC layer 385 covers at least the top of magnetic yoke 145 and theimmediately surrounding area of the head. As seen in FIG. 17A and moreclearly in FIG. 17B, a hard protective wear layer 385 covers magneticyoke 145 and insulative pedestal 300. Protective layer 385 exhibits aKnoop hardness greater than 700 Knoop and preferably greater than 800Knoop. The hardness of protective layer should be within the range ofgreater than approximately 700 Knoop to approximately 2000 Knoop. Onematerial that is satisfactory for formation of protective wear layer 385is diamond like carbon (DLC).

To form such a DLC wear layer 385, DLC layer 385 is chemically vapordeposited and patterned. More specifically, both DLC layer 385 andadhesion layer 380 are reactive ion etched to leave a DLC wear layer385' over magnetic yoke 145 and insulative pedestal 300 as shown in FIG.18. Prior to exposing head 100 to this reactive ion etch, the uppersurface of head 100 is covered with a layer of photoresist (not shown).The photoresist layer is patterned to include unprotected open regionsfor those portions of the head external to frame 325. In this manner,when the head is subjected to the reactive ion etch, the portion of DLClayer 385 external to frame 325 is etched away and the remaining portionof DLC layer 385 is protected and remains as DLC layer 385'.

An alternative to the above described photoresist masking approach topatterning DLC layer 385 into DLC layer 385' is to cover head 100 with ametal layer such as chromium. For example, a relatively thin photomasklayer (not shown) of chromium is sputtered over the DLC layer. In thisparticular example, the photomask layer is approximately 500 A° thick.The metal photomask layer is photo-patterned and etched to expose DLCareas which are to be excavated by reactive ion etching. The DLC layeris then reactive ion etched to the desired DLC structure.

More detail is now provided with respect to the formation of DLCprotective wear layer 385. Before DLC protective wear layer 385 isactually laid down on silicon adhesion layer 380, adhesion layer 380 issputter cleaned. In the course of performing this sputter cleaning,approximately 200A° of the upper surface of silicon adhesion layer 380is removed. More particularly, the silicon adhesion layer is sputtercleaned in a SAMCO plasma machine, Model No. PD-200D (Plasma EnhancedCVD System For DLC Deposition and Etching), hereafter the "plasmamachine". This sputter cleaning is performed with Argon in a plasmawithin the plasma machine vessel at a pressure of 70 mTorr with 180watts RF input power at a frequency of 13.56 MHz. The flow rate of Argonis approximately 100 sccm. The partially complete head 100 is situatedon a 6 inch diameter cathode (ie. the energized electrode) of the SAMCOplasma machine, Model PD-200D, for approximately 3 to approximately 4minutes.

Immediately after the Argon plasma cleaning (sputter etching) iscomplete, the input power is reduced to 110-150 Watts to the same 6 inchcathode electrode. The Argon source is turned off and a source of liquidhydrocarbon DLC source material is turned on. For example, one DLCsource material that may be used is Part No. S-12 available from SAMCO,Sunnyvale, Calif. The pressure within the vessel is approximately20-approximately 25 mTorr at a flow rate of source material ofapproximately 25 cm³ /min. Although the temperature is not specificallycontrolled during this process, the wafer on which the head isfabricated is situated on a water-cooled cathode while in the plasmamachine. Under these conditions, a DLC deposition rate of approximately1000 A/min is obtained which is maintained until the desired DLCthickness is reached, namely approximately 5μ.

DLC fabricated in this manner results in a DLC layer 385 with a Knoophardness of approximately 800. It is found that DLC layer Knoophardnesses of greater than 700 up to approximately 2000 Knoop produceand acceptably hard wear layer 385 for wear protection purposes. DLCwear layer 385 is then reactive ion etched as described to form DLC wearlayer 385'.

DLC wear layer 385'is machined as shown in FIG. 19B to expose magneticgap region 360 as shown in both FIG. 19A and 19B. DLC wear layer 385'protects head 100, specifically gap region 360 and magnetic poles 345,365, from wear when head 100 is brought into contact with a magneticmedia for recording or playback purposes. By using the techniquesdescribed herein, very narrow gap regions can be produced. The gapwidth, W_(G), is defined to be the width of gap region 360, namely thedistance between pole end 345A and pole end 365A as seen in FIG. 19B.Typical gap widths for head 100 are approximately 0.2 microns toapproximately 1 micron.

It is noted that in one embodiment of the invention, the upper magneticpole elements 345 and 365 are plated directly on magnetic side poles 265and 270, respectively, Advantageously, no intervening structures arerequired between upper magnetic pole element 345 and magnetic side pole265 or between magnetic pole element 365 and magnetic side pole 270.Magnetic pole elements 345 and 365 are thus integral with magnetic sidepoles 265 and 270, respectively.

III. VIA CONNECTION FABRICATION

From the above discussion it will be appreciated that via connectivemembers 112A, 112B and 112C permit the connection of coil structures(190, 235) on one side of substrate 105 to be electrically coupled tostructures on the other side of substrate 105 as seen in FIG. 19B.Unlike other approaches which employ an electrically conductivesubstrate such as silicon, each via hole in the disclosed head 100 neednot be internally coated with insulative material. The disclosed thinfilm head 100 employs an electrically insulative substrate through whichvia holes 110 are formed by laser drilling or other highly positionallyaccurate hole formation technique.

In one embodiment of the invention, via connective members 112A, 112Band 112C are formed as follows: Tungsten (W) is sintered into each viahole. The tungsten is then fired such that it bonds with the tungsten toform a spongy, porous material in the hole. The wafer or substrate withthe via holes therein is then exposed to molten copper. When thisoccurs, the copper wicks up into the porous material in the hole to forma tungsten/copper combination within the hole. Alternatively, the viaholes could be plated with copper, or a thick film copper or gold pasteis placed in the via holes and fired to form the via connective members.

It is noted that subsequent to the formation of via connective members112A, 112B and 112C, a number of etching steps occur which couldpotentially cause damage to these via connective members. For example,assuming that via connective members 112A, 112B and 112C are fabricatedby plating copper in the corresponding via holes 110 in one embodimentof the invention, then if coil layers 190 and 235 are likewisefabricated from copper, the via connective members could potentially bedamaged by the etchant which is used to pattern coil layers 190 and 235.

In one embodiment of the invention wherein coil layers 190 and 235 arefabricated from copper, an ammonium persulfate--ammonium hydroxidesolution is used to pattern or etch these layers. To form this etchant,in one liter of deionized water dissolve 120 gm of ammonium persulfate,and add 64 ml of 30% ammonium hydroxide solution. This is a relativelymild selective etchant which etches copper but does not attack materialssuch as Ni or NiFe. Via caps 120 are made of a material which is notattacked by the selective etchant used to etch coil layers 190 and 235and which. is not attacked by the etchant used to etch seed layer 115away. (It will be recalled that seed layer 115 is the seed layer onwhich via caps 120 are plated.) In this example, via caps 120 are madeof Ni or NiFe. After via caps 120 are plated, the exposed portions ofseed layer 115 are sputterd etched away in one embodiment of theinvention.

Via caps 120 extend beyond the periphery of via connective members 112A,112B and 112C by approximately 20 to approximately 30 microns at thetops thereof in one embodiment where vias 110 exhibit a diameter ofapproximately 150 microns. Via caps 120 thus form a protective coveringsfor the tops of via connective members 112A, 112B and 112C which preventthe via connective members from being exposed to etchants in the stepsof head fabrication subsequent to via connective member formation. Theselective etchants employed in the subsequent etching steps selectivelyattack the subject target material or layer (for example, copper coillayers 190 and 235) but do not substantially erode via caps 120. In thismanner, the integrity of via connective members 112A, 112B and 112C ispreserved.

The material requirements for via caps 120 are that the cap material beplatable and that the material should not be significantly attacked byetchants employed in fabrication steps after via cap formation.Protective material other than Ni and NiFe may be employed as long assuch other materials are not affected by the selective etchant. Thematerial requirements for the selective etchant are that it must be ableto etch the particular electrically conductive material selected forcoil layers 190, 235 and seed layer 275 while not significantlyattacking the via cap 120 material.

In this particular embodiment of the invention, while via caps 120 areused to protect via connective members 112A, 112B and 112C on substratesurface 105A from etchants, exposed vias on the reverse side 105B (seeFIG. 20) of substrate 105 are protected from etchants with photoresist(not shown) during such etching steps. Such a layer of photoresist iscoated and cured on reverse side 105B to provide protection frometchants. The lowermost portions of via connective members 112A, 112Band 112C appear in FIG. 20 as well as the bottoms of the via holes 110through which such via connective members run.

While a thin film magnetic head apparatus has been described above, itis clear that a method of fabricating such a magnetic head apparatus isalso disclosed. Briefly, a method of fabricating a thin film magnetichead including a plurality of layered components is provided. The methodincludes the step of forming a via through an electrically insulativesubstrate which includes first and second opposed major surfaces, thevia including an interior side surface. The method also includes thestep of filling the via with electrically conductive material in contactwith the interior side surface of the via to form a via connectivemember extending between the first and second surfaces of the substrate.The method further includes the step of forming a protective via capatop the via connective member at the first surface of the substrate.The method still further includes the step of forming a thin film headatop the first surface of the substrate by building up components of thehead layer by layer, the forming a thin film head step including thestep of forming a coil for exciting the head by etching, with anetchant, portions of a layer of electrically conductive material withinthe head. In this method, the via protective cap is fabricated of amaterial which is substantially resistant to etching by the etchant.

The foregoing has described a thin film magnetic head in which the viaconnective members are protected from potential adverse effects ofetching steps used to fabricate the head. Advantageously, the disclosedthin head achieves a very narrow gap width which results incorrespondingly high density magnetic recording capabilities. The thinfilm head can be fabricated without excavating a recess within thesubstrate to contain the head. Moreover, the disclosed thin film headcan be fabricated in large quantities using thin film semiconductorfabrication equipment.

While only certain preferred features of the invention have been shownby way of illustration, many modifications and changes will occur. Itis, therefore, to be understood that the present claims are intended tocover all such modifications and changes which fall within the truespirit of the invention.

What is claimed is:
 1. A method of fabricating a thin film magnetic headapparatus including a plurality of layered components, the methodcomprising the steps of:forming a via through an electrically insulativesubstrate which includes first and second opposed major surfaces, thevia bordering an interior side surface of the substrate; filling the viawith an electrically conductive material in contact with the interiorside surface of the substrate to form a via connective member extendingbetween the first and second opposed major surfaces of the substrate;forming a protective via cap atop the via connective member andextending from the first major surface of the substrate; and forming amagnetic yoke and coil portion of the thin film magnetic head overlyinga portion of the first major surface of the substrate, the magnetic yokeand coil portion being separated from the protective via cap, themagnetic yoke and coil portion being formed by building up components ofthe magnetic yoke and coil portion in a plurality of layer depositionand etching steps, the step of forming a magnetic yoke and coil portionof the thin film magnetic head including the step of forming a coil forexciting the thin film magnetic head the coil being formed by depositinga layer of the electrically conductive material encircling magneticpoles of the magnetic yoke and etching, with an etchant, portions of thelayer of the electrically conductive material; wherein the viaprotective cap being fabricated of a material which is substantiallyresistant to etching by the etchant.
 2. The method of fabricating a thinfilm magnetic head apparatus of claim 1 wherein the electricallyconductive material is plated in the via.
 3. The method of fabricating athin film magnetic head apparatus of claim 1 wherein the via is formedby laser drilling though the substrate.
 4. The method of fabricating athin film magnetic head apparatus of claim 1 wherein the coil isfabricated from copper and the via protective cap is fabricated fromNiFe.
 5. The method of fabricating a thin film magnetic head apparatusof claim 4 wherein the etchant is a mixture including ammoniumpersulfate and ammonium hydroxide.
 6. A method of fabricating a thinfilm magnetic head apparatus including a plurality of layeredcomponents, the method comprising the steps of:forming a via through anelectrically insulative substrate which includes first and secondopposed major surfaces, the via bordering an interior side surface ofthe substrate; filling the via with an electrically conductive materialin contact with the interior side surface of the substrate to form a viaconnective member extending between the first and second opposed majorsurfaces of the substrate; forming a protective via cap atop the viaconnective member and extending from the first major surface of thesubstrate; and forming a magnetic yoke and coil portion of the thin filmmagnetic head overlying a portion of the first major surface of thesubstrate, the magnetic yoke and coil portion being separated from theprotective via cap, the magnetic yoke and coil portion being formed bybuilding components of the magnetic yoke and coil portion in a pluralityof layer deposition and etching steps, the step of forming a magneticyoke and coil portion of the thin film magnetic head including thesubsteps of:depositing a lower magnetic layer of the magnetic yoke onthe first major surface of the substrate, the lower magnetic layerhaving first and second opposed ends; depositing a plurality of layersof magnetic material at the first end of the lower magnetic layer tobuild-up a first side pole of the magnetic yoke having a first top end;depositing a plurality of layers of magnetic material at the second endof the lower magnetic layer to build-up a second side pole of themagnetic yoke having a second top end; forming a coil element around oneof the first and second side poles concurrently with formation of thefirst and second side poles, the step of forming a coil elementincluding depositing a layer of the electrically conductive materialencircling the first and second side poles of the magnetic material andetching, with an etchant, portions of the layer of the electricallyconductive material; depositing a first upper magnetic pole element ofthe magnetic yoke at the first top end, the first upper magnetic poleelement including a first gap end extending toward the second top end;forming a gap region of nonmagnetic material at the first gap end of thefirst upper magnetic pole element; and depositing a second uppermagnetic pole element of the magnetic yoke at the second top end, thesecond upper magnetic pole element including a second gap end situatedadjacent the gap region; the via protective cap being fabricated of amaterial which is substantially resistant to etching by the etchant. 7.The method of fabricating a thin film magnetic head apparatus of claim 6wherein the electrically conductive material is plated in the via. 8.The method of fabricating a thin film magnetic head apparatus of claim 6wherein the via is formed by laser drilling though the substrate.
 9. Themethod of fabricating a thin film magnetic head apparatus of claim 6wherein the coil is fabricated from copper and the via protective cap isformed
 10. The method of fabricating a thin film magnetic head apparatusof claim 9 wherein the etchant is a mixture including ammoniumpersulfate and ammonium hydroxide.